Communications: Radio goes underground: Communicating in mine tunnels has been taken seriously by radio and microwave engineers only in the last decade

Communicating in tunnels is becoming more the science of radio wave propagation than a form of echo art. That is welcome news for miners, whose daily living in the Earth´s catacombs depends on reliable communications. Serious research in underground communications began in Europe and the United States only 10 years ago, but it has progressed to the point where European mines are using radio not only for speech, but also for the remote control of mining machines.